In creating a more natural question-and-answer flow, you may wish to have the bot recall and refer to the last response the user has given. Using the <that> tag allows this to happen. This tag retains the last template response as the “subject” of the next pattern, allowing you to create a two-step question-and-answer pattern. You can think of it as <that> being used to modify the value of the subsequent pattern, allowing the pattern to match only if the value of <that> was the bot’s last response.

For example, the user may ask about a particular item or service, let’s say Storytime. Since the availability and location of this service differs depending on the branch library in question, the bot will ask where the user would like to attend Storytime. When the user replies with a branch name, the bot can provide the appropriate information about Storytime at that branch.

<category>

<pattern>Where is Storytime</pattern>

<template>At which branch do you wish to attend Storytime?</template>

</category>

<category>

<pattern>Main Library</pattern>

<that>At which branch do you wish to attend Storytime?</that>

<template>Storytime at Main Library is held in the Children's Room.</template>

</category>

<category>

<pattern>West Branch</pattern>

<that>At which branch do you wish to attend Storytime?</that>

<template>Storytime at West Branch Library is held in the alcove by the bay window.</template>

<category>

Here the user will receive the correct information about the branch where he or she wishes to attend the program, but the above patterns “Main Library” and “West Branch” will generate the assigned response only if they follow the question “At which branch do you wish to attend Storytime?” So a user who simply enters the branch name to find other information about the branch won’t get the “Storytime” response.

The <set> tag is used to save an input value for later use or reference. The <get> tag is used to retrieve the saved value. This can also be useful in preparing or collecting information for later processing (as for passing to another database).

Let’s look at the <set> tag first. In its simplest form, a <set> can appear alone when used to assign a value or characteristic to the bot itself. This is similar to the bot properties settings. An example would be gender. The following singleton tag sets the bot’s gender to male.

<set_male/>

However, the <set> tag is more frequently used to assign a value to a specific variable or term. For example:

• <set_it>horse</set_it>—assigns the value “horse” to the variable it.
• <set_location>West Branch</set_location>—assigns the value “West Branch” to the variable location.
• <set_name>Emma</set_name>—assigns “Emma” as the name of the client.
• <set_xxx>X</set_xxx>—creates a variable xxx and assigns the value “X” to it.

Additionally, <set name=“x”></set> can be used to extend AIML by creating custom tags for foreign language pronouns or predicates. In this way, an infinite variety of variables and values can be incorporated.

Let’s now turn to the <get> tag. This tag can also appear alone rather than in a pair, though it usually appears with a matching <set> tag. On those occasions where <get> appears without a <set> tag, it is accessing one of a set of predetermined property values set outside of the AIML code or process. These values are referred to as “Read Only.” Table 4.1 lists Read Only <get> tags.

It is more usual, however, for the <get> tag to refer to a value assigned by a <set> tag in the same or another AIML file. These values usually are associated with a particular user and can only appear in the <template> of a category. Here are some of the standard <get> tags of this kind:

<get_name/> user's name

<get_topic/> a previously assigned topic of conversation

<get_it/> the value assigned to “it”

<get_location/> the user's geographic location

Now let’s look at an example of a <set><get> combination. Here the user is asked for a branch name; this name is then used when answering the user’s question about hours.

<category>

<pattern>my branch is *</pattern>

<template>

<set name=“branch”><star/></set> I'll remember your branch is <star/>.

</template>

</category>

<category>

<pattern>What are your hours</pattern>

<template>

Hours for the <get name=“branch”/>: Monday through Friday 9 A.M. to 5 P.M.

</template>

</category>

The <topic> tag expands upon the functionality of the <set><get> pair by collecting together a group of categories to which a single topic value can be assigned. <topic> tags appear in pairs surrounding a set of categories that all refer to that topic. If a topic value is matched in a user input, those categories associated with it are searched first for pertinent pattern matches. Thus, the use of <topic> tags allows different responses to a single pattern depending on the topic in which it appears. This provides a more natural flow of conversation as well as allowing more specificity in template responses. Here is an example. The following conversation offers differing responses to the same questions depending on the user’s original input (or lack thereof):

<category>

<pattern>I like to *</pattern>

<template>Yes, <set name=“topic”><star index=“1” /></set> is fun. Let's talk about it?

</template>

</category>

<topic name=“read”>

<category>

<pattern>where do you like to <get_topic/></pattern>

<template>I like to read curled up on my counch.</template>

</category>

<category>

<pattern>what do you need to <get_topic/></pattern>

<template>Just my glasses and a good book.</template>

</category>

</topic>

<topic name=“sing”>

<category>

<template>I'm happy to sing anywhere. But, for the sake of others, I try to limit myself to the shower and my car.</template>

</category>

<category>

<pattern>what do you need</pattern>

<template>I either turn the stereo up to help drown out my sour notes. Or I make sure anyone else in the house has earplugs. </template>

</category>

</topic>

<category>

<pattern>where do you like to <get_topic/></pattern>

<template>Where do I like to go to do.. What?</template>

</category>

<category>

<pattern>what do you need<get_topic/></pattern>

<template>I really cannot answer that question without more info. What do you like to do?</template>

</category>

The above example is very simple, but the value is easily seen if you have branches with differing hours of service, material types with different loan periods, etc.

Above you can also see an example of the use of the <get_topic/> tag. You can use this tag to incorporate the assigned value of <topic> into your template responses.

The <topic> tag can also be set inside a template to direct further conversation to the stated topic, as in this example:

<category>

<pattern>I want to go to *</pattern>

<template>Can I provide you with any additional information about that branch? <topic name=“West Branch”></template>

</category>

Here, subsequent conversations will revolve around West Branch until the topic is reset.

The <person> tag provides a pronoun-swapping function that allows the bot to make sensible responses to a variety of statements. The <person> tag is a singleton shorthand for the sequence <person/><star/></person>. The most common use of the tag is to operate on a <star/> variable string to replace included pronouns. In the following example the user states:

The branch is too far from me.

The bot responds:

I understand the branch is too far from you. What could we do to help?

<category>

<pattern>the branch * </pattern>

<topic> I understand the branch <person/>. What could we do to help?

</category>

Similar issues could be addressed with the same code:>

User: The branch is too cold for me.

Bot: I understand the branch is too cold for you. What could we do to help?

User: The branch is confusing to me.

Bot: I understand the branch is confusing to you. What could we do to help?

Use of the <think></think> tag pair allows the inclusion of scripting that you don’t wish to be displayed (or read) to the user. It can be used to retain a topic for multiple questions or information that is being used to narrow the scope of a particular question.

However, possibly the most important use of the <think> tag in basic-level chatbots is to pass queries to other databases or information resources. This process requires a combination of JavaScript coding in the HTML frame within which the bot’s data input field appears and AIML coding within the specific category.

Let’s look at a fairly simple example. First, here’s the AIML coding to pass a search from the bot to the Ohio Web Library (which hosts a number of magazine and journal indices). The <think> tags are used to hide the process of passing the search and searcharg values to the JavaScript code in the HTML frame. Basically, what happens here is that if a user asks for an article on a topic, the AIML code responds with the text about passing the search to Ohio Web Library while saving the value of the wildcard * as <star/> and assigning the value ohweblib to search. We have used the term search to identify the location where the search is to be conducted and, in some cases, the type of search to be completed (keyword, author, title, audiovisual materials only, etc.)

<category>

<pattern>ARTICLE ON *</pattern>

<template>

I'm opening a link to The Ohio Web Library which contains a variety of magazine and journal articles to help you. If you don’t see the results, please turn off your pop-up blocker.

<think>

<set name=“searcharg”><star/></set>

<set name=“search”>ohweblib</set>

</think>

</template>

</category>

Here’s the HTML code that follows the query input form and receives the values from the category above. When an input is processed, the template contained within the HTML file is processed along with that included in the AIML file. This template checks to see if a search value has been identified in the AIML code. If such a value exists, the template contains JavaScript that opens a new window containing the results of a search done on the appropriate website, using the value of searcharg as the search term. The specific search conditions are followed by <set name=“search”>nosearch</set> to return the bot to a “nonsearching” mode for future queries.

<template>

<condition name=“search” value=“ohweblib”>

<script language=“JavaScript”>var myWindow =window.open('http://ohioweblibrary.org/?q=<get name=“searcharg”/>&defaultcat=All');

</script>

</condition>

<set name=“search”>nosearch</set>

</template>

More complete instructions for creating code to pass searches to other resources are contained in chapter 5.

Obviously there will always be some questions for which you have not programmed a response. For these questions, it is useful to create a simple category to respond to users with either a request for additional information or an explanation that the information they are seeking isn’t yet part of the bot’s knowledge base. Below are examples of both types of “ultimate default categories.”

<category>

<pattern>*</pattern>

<template>

I need more information to help you. Are you looking for something to check out or do you have a question about this topic?</template>

</category>

<category>

<pattern>*</pattern>

<template>

<random>

<li>I'm sorry. I don't recognize your question. Please ask one of our human staff for assistance.</li>

<li>I'm sorry. I don't have a response to that. Check back in a few days and I may.</li>

<li>I don't have an answer for that right now. Tell me again what you're looking for. </li>

</random>

</template>

</category>